Substrate With Raised Edge Pads

ABSTRACT

A separable electrical connection may be provided with a landside pad on one of two electrical components to be joined. The landside pad may be made up of two parts, including a flat portion and a raised edge formed on the flat portion. In some embodiments, the raised edge may have a closed geometric shape. Then, a socket contact engaging the junction between the flat portion and the raised edge is prevented from sliding off of the landside pad by the raised edge. In addition, dual areas of electrical connection can be established between both the flat portion and raised edge of the landside pad and the correspondingly shaped pair of portions on the socket. This increases the electrical efficiency of the connection and its security.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No. 11/315,854, filed on Dec. 22, 2005.

BACKGROUND

This invention relates generally to separable electrical interconnection systems and, particularly, to electrical sockets for connecting two electrical components.

In conventional electrical sockets, a socket contact may contact a generally flat pad of a substrate. The pad, often called a landside pad, is connected to one electrical component and the socket contact is connected to another.

As substrate landside pads are shrunk to improve electrical performance, the socket contacts may tend to slide off the pads. In addition, while the pads are shrunk, the contact resistance between the socket contacts and the substrate landside pads may still be relatively high due to the small contact area.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an enlarged, cross-sectional view of one embodiment of the present invention;

FIG. 2 is an enlarged, cross-sectional view at an early stage of manufacture of the embodiment shown in FIG. 1 in accordance with one embodiment of the present invention;

FIG. 3 is an enlarged, cross-sectional view at a subsequent stage in accordance with one embodiment of the present invention;

FIG. 4 is an enlarged, cross-sectional view at a subsequent stage in accordance with one embodiment of the present invention;

FIG. 5 is an enlarged, cross-sectional view at a subsequent stage in accordance with one embodiment of the present invention;

FIG. 6 is an end view of a socket contact in accordance with one embodiment of the present invention;

FIG. 7 is a cross-sectional view taken generally along the line 7-7 in FIG. 1;

FIG. 8 is a vertical cross-section through a portion of a motherboard with a processor mounted thereon, in accordance with one embodiment; and

FIG. 9 is a system depiction for one embodiment.

DETAILED DESCRIPTION

Referring to FIG. 1, a first electrical component 12 may be electrically coupled to a second electrical component 18. In one embodiment, the component 12 may be an integrated circuit package, such as a packaged processor. In one embodiment, the component 12 may be land grid array (LGA) package. In one embodiment, the component 18 may be a socket for an integrated circuit, such as a processor. In one embodiment, the component 18 may be a land grid array (LGA) socket.

Electrical sockets may be used to provide separable electrical connections between a variety of different electrical components, including integrated circuit package to motherboard. However, many other socket interconnections may also be contemplated.

The separable electrical connection 14 includes a generally U-shaped, downwardly projecting landside pad 14 a and an upwardly projecting socket contact 20. Thus, the separable electrical connection 14 includes two interfitting parts which may be pluggingly interconnected by placing the component 12 on top of the component 18, for example, using a pick and place machine.

The landside pad 14 a includes a flat, central disc portion 24 and a peripheral, raised ring 22, which may extend downwardly towards the component 18 relative to the flat disk portion 24. While a ring is shown, other closed shapes, such as triangles, rectangles, and ovals, may also be used. Also, open geometric shapes may be used.

As better shown in FIG. 7, the ring 22 surrounds the flat disc portion 24 of the landside pad 14 a. The socket contact 20 (FIG. 6) is curved, in one embodiment, and may have a radius of curvature approximately the same as the radius of curvature of the ring 22. However, the contact 20 may be only a cylindrical segment, of about a 60° arc, in one embodiment. Using the cylindrical segment, as opposed to the entire cylinder, makes it easier to align and assemble the components 18 and 12.

Thus, contact may be achieved between the contact 20 and the upstanding portion of the ring 22, as well as between the flat end of the contact 20 and the flat disc portion 24 of the landside pad 14 a. The components 12 and 18 may be held together through the application of an external load, for example, through springs.

This double contact area, in some embodiments, increases the extent of electrical connection and increases the electrical performance. Moreover, outward, disengaging sliding movement between the contact 20 and the landside pad 14 a is effectively reduced or eliminated.

A solder resist 16 may be maintained between the components 12 and 18 in some embodiments. However, any insulator may also be used.

Referring to FIG. 2, initially, the electrical component 12 has flat disc portion 24 formed thereon. In practice, while only portions 24 are shown, a large number of such pads may be formed in an array in some embodiments.

Next, as shown in FIG. 3, photoresist 28 may be deposited over the structure, patterned, and openings 26 formed. Then, as shown in FIG. 4, metal may be deposited into the openings 26. If the openings 26 are ring-shaped, the rings 22 may be formed by the metal deposition process. In one embodiment, the metal may be copper and may be formed by plating. The portion 24 may also be copper in one embodiment.

Referring now to FIG. 5, the photoresist 28 may be removed and a solder resist layer 16 may be applied so that only portions surrounding the landside pads 14 a are coated with the solder resist.

Referring to FIG. 8, in accordance with some embodiments of the present invention, the technology described above may be utilized to electrically couple an integrated circuit to a printed circuit board such as a motherboard. For example, in FIG. 8, the printed circuit board 38 may be a motherboard. A component 18, in the form of a socket which contains many contacts, may be situated on the printed circuit board 18, and the contacts are connected to the motherboard 38 by suitable electrical connections (such as solder joints) along the interface 42. Input/output (I/O), power, and ground connections may be supplied through the socket contacts.

Also mounted on the socket 18 may be a substrate 32, an integrated circuit chip 30, and heat spreader 31 which, together, make up the component 12. The interface 36 may include the connections between the elements 14 a and 20. A frame 40 which is part of the socket 18 may be applied over the heat spreader 31 to supply a force to hold the component 12 on the component 18.

In one embodiment of the present invention, the component 12 may be a land grid array package using an array of terminals called landside pads in the interface 36. An array of contacts, in the form of contacts 20, may be formed on the socket 18 that mate with the elements 14 a on the component 12.

The contacts on the socket 18, along the interface 42, in one embodiment, may be fabricated from a metal (such as copper-beryllium alloys) or other suitable material and are coupled to the socket 18. The contacts provide all the electrical connections including I/O, power and ground between the component 12 and the motherboard 38.

In one embodiment, the chip 30 is a processor coupled to the motherboard 38. As shown in FIG. 9, the motherboard 38 may include connections 44 to other devices including a memory such as a dynamic random access memory 48, a static random access memory 50, and an I/O interface 46. Thus, a processor 30 a may be coupled to other devices through the motherboard 38.

Thus, in some embodiments, the contact includes a cylindrical portion which makes contact near its end with the raised edge of the landside pad. The cylindrical portion is less than an entire cylinder and may only be a 60° portion of a cylinder. The flat end of the contact makes contact with the landside pad flat portion. Thus, two transverse surfaces contact, increasing the efficiency of the electrical connection. That is, the cylindrical portions of the raised edge and the contact, as well as the free end of the contact and the flat portion of the landside pad. At the same time, the raised edge of the landside pad prevents the contact from slipping off the landside pad, particularly with relatively small landside pads.

References throughout this specification to “one embodiment” or “an embodiment” mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation encompassed within the present invention. Thus, appearances of the phrase “one embodiment” or “in an embodiment” are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be instituted in other suitable forms other than the particular embodiment illustrated and all such forms may be encompassed within the claims of the present application.

While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention. 

1. A method comprising: forming an electrical connection between two electrical components using a contact on one component and a landside pad on the other component, said landside pad having a raised edge.
 2. The method of claim 1 including providing a landside pad with a closed raised edge.
 3. The method of claim 2 including providing a landside pad with a circular raised edge.
 4. The method of claim 1 including providing a socket contact that has a shape that conforms to the shape of said landside pad raised edge.
 5. The method of claim 4 including providing a circular raised edge and a circular contact.
 6. The method of claim 5 including providing a raised edge and a contact with substantially the same radii of curvature.
 7. The method of claim 1 including contacting the landside pad with said contact on two different surfaces.
 8. The method of claim 7 including providing two transverse contacting surfaces between said pad and said contact.
 9. The method of claim 1 including forming said landside pad by forming a first substantially planar landside pad portion and depositing a second layer to form said raised edge.
 10. A method comprising: forming a substantially planar portion of a landside pad on an electrical component; and forming a raised edge on said portion by depositing a metal on said substantially planar portion.
 11. The method of claim 10 including forming said raised edge in a closed geometric shape.
 12. The method of claim 11 including forming said raised edge in a circular shape.
 13. The method of claim 10 including forming the planar portion of said landside pad, patterning a mask over said planar portion and depositing a metal in the mask formed over said planar portion to form said raised edge.
 14. The method of claim 13 including providing solder resist around the resulting landside pad. 